'''
【程序56】
题目：画图，学用circle画圆形。　　　
1.程序分析：
2.程序源代码：

'''
if __name__ == '__main__':
    from tkinter import *

    canvas = Canvas(width=500, height=500, bg='yellow')  
    canvas.pack(expand=YES, fill=BOTH)                
    k = 1
    j = 1
    for i in range(0,20):
        canvas.create_oval(200 - k,200 - k,200 + k,200 + k, width=1)
        k += j
        j += 0.8

    mainloop()
